1. Field of the Invention
The invention relates to liners or inflations for teat cup assemblies for automatic milking machines. In one of its aspects, the invention relates to a teat cup inflation having a vent located in the mouthpiece. In another if its aspects, the invention relates to a teat cup inflation having a multi-sided cross-section. In another if its aspects, the invention relates to a teat cup inflation having an air passageway formed in the inflation to vent air from the upper to the lower portion of the inflation.
2. Description of Related Art
Teat cup assemblies are used in automatic milking machines for milking cows. The teat is inserted into the teat cup assembly. During the milking operation, a vacuum is maintained in the milking machine claw, dilating the teat orifice, drawing milk from the teat, through the barrel portion of the inflation and through the short milk tube section into the milker claw. The pulsation chamber between the shell and the barrel is connected to a pulsator on the milking machine. The pulsator periodically opens a connection between the pulsation chamber and atmospheric pressure, collapsing the liner's barrel to a closed position. When in this closed position, the barrel compresses the teat tissue to close the teat orifice, interrupting the flow of milk from the teat. The flow of milk from the teat resumes when the barrel returns to a normally open position in response to the pulsator subsequently connecting the pulsation chamber to vacuum.
Heretofore, a vent has been placed in either the short milk tube section of the inflation or in the claw to assist the flow of milk away from the milking cluster, and onward through the milk transport system. When the vent is placed in the short milk tube, not only the claw, but also the short milk tube is kept clear of milk by the air flow entering the vent. Venting the inflation in the mouthpiece improves flow of milk away from the teat, while continuing to assist milk flow through the short milk tube and claw. Locating the vent in the mouthpiece also advantageously limits the vacuum experienced by the teat.
Traditional milking inflations are round in cross-section and are made easily in machine molds, simplifying the manufacture of the inflation. It is apparent, however, that both natural calf suckling and hand milking, both of which are generally accepted as allowing complete and effective milking without undue stress to the teat, begin with a non-round structure presented to the teat. The structure becomes even less round as each compression or suction cycle of milking proceeds, either by motion of the tongue against the palate in the case of a suckling calf, or by closure of the hand in the case of hand milking. It is now generally accepted that non-round cross-sections of the liner barrel can provide effective milking; examples being oval, triangular, square, and corrugated inflation barrels. U.S. Pat. No. 2,502,362 to Babson et al., issued Mar. 28, 1950, describes a teat cup assembly comprising a rigid tubular outer shell surrounding a flexible tubular inflation wherein the inflation and the interior surfaces of the shell have a triangular cross-section.
GB644168 to Burry, published Oct. 4, 1950 discloses a teat cup liner 1 that has a bulbous mouthpiece 3 that is provided with a small hole 10 for the limited admission of air to the space within the mouthpiece. The barrel of the teat cup liner 1 has a flattened cross section that can be oval or elliptical. The small hole is said to be next to the udder and the limited admission of air into the space reduces the degree of suction and avoids the application of excessive vacuum on the udder without detriment to the good milking vacuum applied lower down at the orifice of the teat. The orifice can be metered and formed with a rivet-like device.
DE1607027 to Bildshausen et al., published Jul. 9, 1970 discloses a liner 4 having a ventilation hole 18 located at the head 2 of the liner 4, and one or more grooves that run lengthwise along the shaft of the liner.
U.S. Pat. No. 7,578,260 to Lauren AgriSystems, Ltd. discloses a liner that includes a vent in the milk tube below the teat position. Lauren contemplates different liner cross-sectional configurations and channels are located at the apex of a collapsed triangular liner.